It is well known, that cocaine has a variety of pharmacological actions, primarily a strong CNS stimulation and local anesthetic action. These effects are accompanied by high toxicity and dependence liability. (see for example R. L. Clarke et al in Journal of Medicinal Chemistry 16(11), 1261-1267 (1973).
The dependence liability is thought to be related to a combination of cocaine's powerful stimulant activity, short term of action, and rapid onset of action together with its strong dopamine-releasing properties. Further it is well known, that cocaine also possess powerful dopamine reuptake inhibiting activity. It is believed, that compounds having long lasting selective dopamine reuptake-inhibiting properties, and being devoid of dopamine releasing properties, will be extremely useful as a novel type of antidepressant and anti-Parkinsonian agent. Furthermore such compounds will be extremely useful in the treatment of drug addiction, and especially in the treatment of cocaine addiction or misuse.
During the years many attempts have been made to optimize upon the properties of cocaine. Many derivatives of cocaine and of its isomers have been synthesized. See for example R. L. Clarke et al in Journal of Medicinal Chemistry 16(11), 1261-1267 (1973) and F. Ivy Caroil et al in Journal of Medicinal Chemistry 34, 883-886 (1991). Many of these derivatives and probably most pronounced the derivatives of R. L. Clarke et al above are very powerful stimulant compounds and have been found to be very potent dopamine reuptake inhibitors. However none of the cocaine derivatives synthesized until today have been found to be devoid of undesired side effects. R. L. Clarke et al in above paper notes at page 1265, that an enantiomer (trans isomer) of a closely related compound (cis isomer as is cocaine) was not stimulant, and at the same page, that moving a 2-carboxy function from an axial (cis isomer) to an equatorial configuration (trans isomer) gave a compound which was inactive in the Iocomotor screen (&gt;256 mg/kg), but appeared to produce a slight stimulation. P. C. Meltzer et al in Journal of Medicinal Chemistry, 36(7), 855-862 (1993) notes that the trans isomers are biologically inactive.
Throughout the literature all efforts of derivating cocaine have focused upon optimizing the dopamine reuptake inhibiting properties and ligand affinity by synthesizing further cis isomers (just as cocaine), undoubtedly because these compounds have been found to be the most potent dopamine reuptake inhibitors as well as the most potent ligands in various binding assays. This also includes the findings published by F. Ivy Carroll et al in J. Chem. Soc. Chem. Commun. pp. 44-46 (1993).